Migrate Deckard from socket_wrapper to Linux namespaces

Migration from socket_wrapper to Linux namespace is mostly done, some refactoring has been done as a side-effect.

TODO:

• Some cleanup/refactor is still needed especially in regards to parsing and handling of configuration.
  • Configuration parsing would need some more time, so I think it's good enough for now.
• Integrate to CI. Creation of namespaces require running the Docker image as --privileged. Deckard will now depend on tshark/dumpcap/wireshark for PCAP capture.
• Code review of the refactor.
• Update the docs.

Note: test:comparitive:kresd will fail because of the change to internal representation of tests.

Fixes #42 (closed)